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skrap1r0n
2004-May-03, 03:40 AM
OK I probably should know this, But I don't so I'm asking...

In Cartes Du Ciel, I have the Ecliptic placed on the map. Now, Is this the Earths Ecliptic or the planetary Ecliptic? I know all planets Orbit in the same general plane, however they seem to stagger away from the ecliptic. Jupiter is about 1 1/4 degrees off the ecliptic, Saturn seems to be about 2 degrees off the plane, Mars is about 1 degree off and Venus is about 3.5 degrees off.

Is this about standard? I know the planets appear to do a little loop as we approach them and pass them, is this what I am seeing?

Lorcan Faol
2004-May-03, 03:50 AM
The Ecliptic is the path that the Sun takes across the sky of the Earth, and most of the other planets follow closely to that path, from our point of view, but not perfectly.

skrap1r0n
2004-May-03, 03:58 AM
The Ecliptic is the path that the Sun takes across the sky of the Earth

ok well this is actually a suprise to me, I thought it may be our path around the sun. But now i know, and knowing is half the battle

Peter B
2004-May-03, 04:07 AM
The Ecliptic is the path that the Sun takes across the sky of the Earth

ok well this is actually a suprise to me, I thought it may be our path around the sun. But now i know, and knowing is half the battle

:D It's the same thing, skrap1r0n. The Earth orbits the Sun. The plane of that orbit is the Ecliptic. However, as we see the Sun rise and set, following a path across the sky, by definition, that's also the Ecliptic.

And as Lorcan Faol said, the other planets orbit pretty much in the same plane as the Earth. That is, within a couple of degrees. The only exception is Pluto.

milli360
2004-May-03, 10:45 AM
And as Lorcan Faol said, the other planets orbit pretty much in the same plane as the Earth. That is, within a couple of degrees. The only exception is Pluto.
This webpage (http://nssdc.gsfc.nasa.gov/planetary/factsheet/): Mercury is 7, Venus is 3.4, Saturn is 2.5. Pluto is 17.2.

skrap1r0n
2004-May-03, 04:11 PM
And as Lorcan Faol said, the other planets orbit pretty much in the same plane as the Earth. That is, within a couple of degrees. The only exception is Pluto.
This webpage (http://nssdc.gsfc.nasa.gov/planetary/factsheet/): Mercury is 7, Venus is 3.4, Saturn is 2.5. Pluto is 17.2.

Wow, I wasn't far off considering I was using My 3.5 FoV as an tool to guesstimate

milli360
2004-May-03, 04:27 PM
Wow, I wasn't far off considering I was using My 3.5 FoV as an tool to guesstimate
How does that work in that software? Is the point of view from the Sun? At the present time, or does it show the entire paths of the planets's revolutions?

skrap1r0n
2004-May-03, 05:58 PM
Wow, I wasn't far off considering I was using My 3.5 FoV as an tool to guesstimate
How does that work in that software? Is the point of view from the Sun? At the present time, or does it show the entire paths of the planets's revolutions?

Well it showed the ecliptic and the planets off it, I have the Eyepiece set for my FoV (3.5 degrees). So I select a planet, center it. and zoom in until the eyepiece reticle is larger, Then I move the eyepiece until it contains both the planet and the ecliptic. As long as one is at the edge of the reticle, I can guess about how far off the ecliptic the planets are by simply estimating the fraction of the reticle seperating the two.

milli360
2004-May-03, 06:14 PM
Since the orbits are inclined, the planets are sometimes "below," sometimes "above" the ecliptic. Right now, Saturn is fairly close to the ecliptic. I was just wondering how you came up with the 2 degrees for Saturn. You must have watched them stagger around their revolution, right?

Brady Yoon
2004-May-03, 07:24 PM
I wonder... Have astronomers ever made a search for planets outside the ecliptic?

Andromeda321
2004-May-03, 07:28 PM
Do asteroid searches count? If so then yes.

skrap1r0n
2004-May-03, 08:15 PM
Since the orbits are inclined, the planets are sometimes "below," sometimes "above" the ecliptic. Right now, Saturn is fairly close to the ecliptic. I was just wondering how you came up with the 2 degrees for Saturn. You must have watched them stagger around their revolution, right?

No, nothing that fancy, Actually As I mentioned, In cartes Du Ciel, I have the Reticle set for 3.5 degrees. All I do is locate Saturn and zoom in until saturn is shwing on one side of the screen and the ecliptic is on the other. Then I project the reticle where saturn is on the edge of the FoV and then take a WAG at how much of the 3.5 degrees takes up the space between Saturn and the ecliptic. Very very unscientific.

skrap1r0n
2004-May-03, 08:19 PM
I wonder... Have astronomers ever made a search for planets outside the ecliptic?

If there were planets outside the ecliptic, I'd be willing to bet that we would have observed them by now. I mean Planet means wanderer right? for the longest time they were thought to be wandering stars.

Besited a planetary mass orbiting off the ecliptic, say in a solar pole orbit would surely show up gravitationally.

milli360
2004-May-04, 02:30 AM
No, nothing that fancy, Actually As I mentioned, In cartes Du Ciel, I have the Reticle set for 3.5 degrees. All I do is locate Saturn and zoom in until saturn is shwing on one side of the screen and the ecliptic is on the other. Then I project the reticle where saturn is on the edge of the FoV and then take a WAG at how much of the 3.5 degrees takes up the space between Saturn and the ecliptic. Very very unscientific.
That's why I was wondering, because Saturn is not 2 degrees off the ecliptic right now, according to my starware. That's why I was surprised that you got so close to the actual value. Could you check it again? I'm interested in differences in different software packages.

If there were planets outside the ecliptic, I'd be willing to bet that we would have observed them by now. I mean Planet means wanderer right? for the longest time they were thought to be wandering stars.

Besited a planetary mass orbiting off the ecliptic, say in a solar pole orbit would surely show up gravitationally.
Not if they were far enough away. But that's the main problem, right? :)

skrap1r0n
2004-May-04, 02:56 AM
That's why I was wondering, because Saturn is not 2 degrees off the ecliptic right now, according to my starware. That's why I was surprised that you got so close to the actual value. Could you check it again? I'm interested in differences in different software packages.
[quote=skrap1r0n]If there were planets outside the ecliptic, I'd be willing to bet that we would have observed them by now. I mean Planet means wanderer right? for the longest time they were thought to be wandering stars.

Well like i said, there was nothing more than a guess based on my known FoV, and comparing it to the planet and ecliptic. I never took any actual measurments, other than a bit of "Kentucky Windage" so to speak. Purely a visual observation leading to a rough guess.